Greek philosopher Plato professed love to be a serious mental disease, while Martin Luther King Jr believed it to be the only force capable of transforming an enemy into a friend.

Shakespeare poetically described love as a smoke made with the fume of sighs and as for songwriters Lennon and McCartney, it is the flower you’ve got to let grow or, most simply, all you need.

For filmmaker Ira Sachs and co-writer Mauricio Zacharias, love is a long-term relationship between two gay men set against the bustling backdrop of modern-day Manhattan.

Underscored by Chopin, Love Is Strange is an elegant character study, which sketches these middle-aged soul-mates with tenderness and heart-breaking intimacy.

Sachs’ film is illuminated by exquisite performances from John Lithgow and Alfred Molina as a married couple who are wary of relying on the kindness of family and friends because “sometimes when you live with people, you know them better than you care to”.

Familiarity breeds not just contempt but also disillusionment, suspicion and, ultimately, aching loneliness.

Ben (Lithgow) and his partner George (Molina) have spent almost four decades together.

Shortly after the happy day, George loses his job as a music teacher at St Grace’s Church and Catholic school in Manhattan because Facebook pictures of the honeymoon in Petra have been brought to the attention of the Archdiocese.

Without George’s income, the couple face the prospect of having to sell their apartment.

George moves in with Ted and Roberto, while Ben seeks shelter with Elliot, Kate and their truculent teenage son Joey (Charlie Tahan), who is far from thrilled about sharing his bunk bed with an elderly gay uncle.

The separation causes friction between family and friends.

“All I know is that after 39 years it’s hard to fall asleep without you,” laments Ben to George.

Love Is Strange treats all of the flawed characters with a delicate and even hand although our hearts invariably belong to the leads.

Lithgow and Molina perform as if they have been sharing the same space for decades, trading gentle touches or longing glances as their carefully ordered world unravels.